During prokaryotic replication, which enzyme is primarily responsible for adding nucleotides to the growing DNA chain?

During prokaryotic replication, which enzyme is primarily responsible for adding nucleotides to the growing DNA chain?

• A. DNA polymerase III
• B. DNA ligase
• C. Primase
• D. Helicase

Answer: (A)

During DNA replication, the enzyme that actually adds nucleotides to the growing DNA strand is a highly processive DNA polymerase, which in bacteria is DNA polymerase III. It works in the 5' to 3' direction, extending the new strand by continually adding nucleotides to the 3' end. This polymerase handles synthesis on both the leading strand (continuous) and the lagging strand (as short Okazaki fragments, each started by a primer and then extended). Primase only creates the RNA primers that start synthesis, helicase unwinds the double helix, and ligase seals the gaps after fragments are joined and primers are removed. While another enzyme, DNA polymerase I, removes primers and fills in with DNA, the major enzyme responsible for adding nucleotides during the bulk of chain elongation is DNA polymerase III.

During DNA replication, the enzyme that actually adds nucleotides to the growing DNA strand is a highly processive DNA polymerase, which in bacteria is DNA polymerase III. It works in the 5' to 3' direction, extending the new strand by continually adding nucleotides to the 3' end. This polymerase handles synthesis on both the leading strand (continuous) and the lagging strand (as short Okazaki fragments, each started by a primer and then extended). Primase only creates the RNA primers that start synthesis, helicase unwinds the double helix, and ligase seals the gaps after fragments are joined and primers are removed. While another enzyme, DNA polymerase I, removes primers and fills in with DNA, the major enzyme responsible for adding nucleotides during the bulk of chain elongation is DNA polymerase III.